The present invention relates to a hot-wire type flow velocity meter and, more particularly, to a hot-wire type flow velocity meter suitable for use in the measurement of fluctuating flow velocity.
The hot-wire type flow velocity meter is a device which is adapted to measure the flow velocity of a fluid by sensing the change of rate of heat transfer from an electric resistor to the fluid. In general, the electric resistor is supported by a suitable supporting member, so that the end of the support member adjacent to the electric resistor is maintained at a high temperature while the other end is maintained at the same temperature as the ambient fluid. In consequence, the heat generated by the electric resistor is consumed by being transferred to the fluid directly from the electric resistor, to the fluid through the supporting member and to other members through the supporting member. As is well known, the heat transfer other than the direct heat transfer to the fluid causes an error in the measurement of the flow velocity. In order to obviate the influence of the heat transfer other than the direct one, it is necessary to diminish as much as possible the heat transfer cross-sectional area of the supporting member or to enlarge as much as possible the heat radiating area of the electric resistor. These measures, however, are quite impractical from the view point of mechanical strength.